Medical waste incinerators are a major source of toxic air
emissions, especially dioxin and cadmium, according to a lengthy
study just released by the California Air Resources Board (CARB),
a state agency. [Page numbers in our text (below) refer to pages
in this new study, which is cited in our next-to-last paragraph.]
The study says the public health risks from breathing these
emissions are unacceptably high. On May 23, the CARB will propose
new air pollution controls on California's medical incinerators;
CARB predicts the new rules will force 129 of the state's 142
incinerators to cease operation because compliance will be too
costly.

Dioxin

The CARB studied dioxin in 1986 and declared it "highly toxic" in
experimental animals. Toxic effects in animals include severe
weight loss, liver necrosis [death of tissue] and hypertrophy
[enlargement], skin lesions, immunosuppression, reproductive
toxicity, teratogenesis [birth defects], carcinogenesis [cancer]
and death. The CARB concluded that dioxin is an animal carcinogen
and a "potential human carcinogen." They also reported that both
acute (short-term) and chronic (long-term) exposure to dioxin has
caused liver damage in humans (pg. 10).

Despite their relatively small size, California's 142 medwaste
incinerators emit substantial quantities of dioxins and cadmium:
16 grams of dioxin each year (pg. 31) and 30 to 40 pounds of
cadmium (pg. 33) each year.

To gather emissions data, the CARB monitored eight medwaste
incinerators. The report notes that, "Although the emissions
tests were not conducted for compliance purposes, we observed
that many of the facilities tested could not meet the particulate
limitations in their permits. In addition, the hydrochloric acid
emissions were elevated...." (pg. 48)

The CARB study indicates that it will cost from $383,000 to
$479,000 to put best available control air pollution control
technology (BACT) (a spray dryer [also called a dry scrubber] and
baghouse filter) on an existing large, regional medwaste
incinerator (pg. 115), of which California has 12.

According to the CARB's data, small medwaste incinerators serving
an individual institution will not be able to afford to install
air pollution equipment that would allow continued operation of
the incinerator after the new dioxin and cadmium regulations
become effective this summer. For these 129 incinerators, the
available alternatives include (a) shut down and use a large,
regional medwaste incinerator; (b) shut down and use off-site
steam sterilization; (c) shut down and use onsite steam
sterilization.

Steam sterilization (also called autoclaving) means heating the
wastes in a metal chamber by filling the chamber with saturated
steam and holding the temperature at 250 degrees Fahrenheit for
30 minutes. It effectively sterilizes wastes, killing viruses and
bacteria. The wastes then go to a landfill. Of these three
options, the cheapest is onsite sterilization; this option would
increase medwaste disposal costs 10 cents per pound, and would
increase patient costs 16 cents per hospital bed per day,
compared to present costs of onsite incineration. The use of
offsite, regional incineration would increase disposal costs 16
cents per pound and would increase average patient costs 41 cents
per bed per day. Onsite steam sterilization would increase
disposal costs 16 cents per pound and would increase patient
costs 42 cents per bed per day. Thus, shutting down its
incinerator and sending wastes out for regional steam
sterilization is the cheapest way for a hospital to come into
compliance with the proposed California air regulations for
cadmium and dioxin (pg. 118).

A different study of medical wastes, by members of the Civil
Engineering Department of University of California at Davis
(cited below in our last paragraph), points out that, in a
typical hospital, infectious waste makes up only about 15% of the
total waste stream. Infectious waste by itself will burn, but the
volume is usually not sufficient to allow heat recovery.
Therefore, the decision to install an incinerator for infectious
waste encourages the burning of other non-infectious wastes. In
effect, a medwaste incinerator is a municipal solid waste
incinerator with 15% of the waste being infectious.

There are, however, a few differences between municipal wastes
and infectious wastes. Plastics make up 3% to 7% of municipal
waste, but 14% to 30% of infectious waste. Because plastics are
the major sources of cadmium and lead, medical waste incinerators
emit more of these toxic metals, per pound of burned waste, than
do municipal incinerators.

Lead is present as a pigment and as a stiffening and
strengthening agent in many plastic items, especially those made
of PVC (polyvinyl chloride). For example, the red bags
themselves, in which "red bag" medical wastes are packaged, is
colored red by a lead compound. Lead is also present in yellow
bags for collecting soiled linens, yellow bedpans, and yellow
tops of urine containers. In plastics, a bright color (yellow,
orange, red, purple) is often an indication of a toxic metal
(cadmium or lead).

Also get: D.C. Hickman, D.P.Y. Chang, and H. Glasser, "Cadmium,
and Lead in Bio-Medical Waste Incinerators," a paper presented at
the 82nd Annual Meeting of the Air and Waste Management
Association at Anaheim, CA, June 25-30, 1989; available free from
Dan Chang, Department of Civil Engineering, Mail ID# 1855,
University of California at Davis, Davis, CA.
--Peter Montague, Ph.D.